secur32: Initialise more pointers in helper to NULL.

This is to avoid calling HeapFree on random pointers when 
DeleteSecurityContext is called on a context that hasn't had a second 
InitializeSecurityContext called on it, which would otherwise intialise 
those pointers.

dlls/secur32/dispatcher.c

diff --git a/dlls/secur32/dispatcher.c b/dlls/secur32/dispatcher.c
index 226de79..4003346 100644
--- a/dlls/secur32/dispatcher.c
+++ b/dlls/secur32/dispatcher.c
@@ -116,6 +116,13 @@
         helper->com_buf_offset = 0;
         helper->session_key = NULL;
         helper->neg_flags = 0;
+        helper->crypt.ntlm.a4i = NULL;
+        helper->crypt.ntlm2.send_a4i = NULL;
+        helper->crypt.ntlm2.recv_a4i = NULL;
+        helper->crypt.ntlm2.send_sign_key = NULL;
+        helper->crypt.ntlm2.send_seal_key = NULL;
+        helper->crypt.ntlm2.recv_sign_key = NULL;
+        helper->crypt.ntlm2.recv_seal_key = NULL;
         helper->pipe_in = pipe_in[0];
         fcntl( pipe_in[0], F_SETFD, 1 );
         close(pipe_in[1]);